Method for extracting titanium slag, tungsten and vandic salt from waste SCR catalyst

Abstract

The invention provides a method for extracting titanium slag, tungsten and a vandic salt from a waste SCR catalyst. The method comprises the steps that the waste SCR catalyst is preprocessed and crushed into slurry by use of a wet method; a sodium hydroxide solution is added into the slurry for reaction; coarse titanium slag power and compression filtrate are obtained by filter-pressing and separating the slurry by use of a plate-and-frame filter press; the coarse titanium slag power is placed into a sulfuric acid solution for cleaning, cleaned with clear water, and then filtered and separated for obtaining titanium slag powder containing titanium dioxide; and the compression filtrate is treated through a waste alkali nanofiltration recovery device, the compression filtrate containing sodium tungstate and sodium vanadate is added into a saturated calcium hydroxide solution for reaction, products from the reaction are subjected to filter pressing, and then calcium vanadate and calcium tungstate mixed solid bodies are obtained through filtering and separating.

Description

technical field [0001] The invention relates to the field of environmental protection, in particular to a method for extracting titanium slag, tungsten and vanadium salts from waste SCR catalysts. Background technique [0002] Selective catalytic reduction (SCR) technology is currently the most widely used and most efficient denitrification technology for removing nitrogen oxide pollutants in flue gas in thermal power plants and coal-fired boilers. More than 90% of the catalyst. This type of denitration catalyst uses heavy metals such as titanium dioxide (65-75%), vanadium pentoxide (1-2%), tungsten trioxide (3-6%) and other heavy metals as the skeleton and catalytic elements, which itself contains certain toxicity. During the use period, a large amount of heavy metals such as chromium, beryllium, arsenic and mercury in the flue gas caused secondary pollution to these catalysts and became harmful materials rich in various heavy metal components. [0003] In August 2014, th...

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Problems solved by technology

[0009] Because these methods need to be roasted at high temperature for many times to obtain high-purity products, they not only require high equipment, large investment, and high energy consumption, but also occupy the raw material resources of relevant downstream refineries and smelters, which belong to redundant construction; This method needs to use excessive sodium carbonate and ammonium salt, which will produce a large amount of carbon dioxide and harmful ammonia, causing serious pollution to the environment

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